Honestly, I find animal-like dragons being ridden by humans more realistic. When the mount is just as intelligent (or more) than his rider, you need some pretty good reasons for why he's letting that little human on. It's believable, however, that a wild creature like these dragons could be captured by humans and bent to their will.

I love how Lackey goes so in depth into the biology of the dragons. The amount of detail she puts into it all is wonderful.